1. Technical Field
The present invention relates to a conversion circuit that converts data to be used for image display, a display drive circuit equipped with the conversion circuit, an electro-optical device equipped with the display drive circuit, and electronic equipment equipped with the electro-optical device.
2. Related Art
It is commonly known that an electro-optical device is equipped with a plurality of scanning electrodes (scanning lines), a plurality of signal electrodes (data lines) and a plurality of pixels provided at position where these scanning electrodes and the signal electrodes intersect one another, wherein a gradation signal (image data) corresponding to the gradation of each pixel is supplied to each of the pixels corresponding to selected ones of the scanning electrodes through the signal electrodes, thereby changing the optical state of each of the pixels. Such electro-optical devices are used not only in stationary type electronic equipment, such as, projectors, TVs and the like, but also in a variety of portable type electronic equipment.
In recent years, many electro-optical devices use the digital drive method in which a plurality of gradation levels is expressed in image display through dividing each frame into a plurality of subframes using digitized image data. Japanese Laid-open Patent Application 2006-215534 (Patent Document 1) describes a technology to increase the number of expressible gradations without increasing the number of subframes in each one frame. Also, Japanese Laid-open Patent Application 2001-209346 (Patent Document 2) describes a technology to display many gradations without using particularly high-speed circuit elements.
As the number of gradations increases as the resolution becomes higher, the data amount of image data to be handled becomes substantially large, such that the image data needs to be processed at high speed. To process such a huge amount of image data at high speed, it is necessary not only to prepare high-speed circuit elements to process the image data but also to newly prepare a high speed data bus, which can lead to a problem of an increased circuit scale.
Also, as the electro-optical device that uses the digital drive method described above achieves higher resolutions with an increase in the number of subframes, its operation speed could reach several ten times the operation speed of an electro-optical device that uses a conventional analog drive method (a method of driving without a subframe dividing scheme). This would make the operation speed extremely high, which could reach several GHz, and lead to problems, such as, increased difficulty in designing, higher power consumption, and the like.